Several firefighters from Helston fell ill at the weekend after tackling an unattended bonfire at Tresprisson on Friday.
Cornwall Fire and Rescue Service, Devon and Cornwall Police and the Environment Agency were all called to the original incident on July 3, when firefighters used two hose reels and a main jet to put out the blaze.
A spokesperson for Cornwall Fire and Rescue Service said: "On Saturday July 4, Cornwall Fire & Rescue Service were made aware of some members of the crew from Helston Community Station who were feeling unwell.
"As a precautionary measure and on information from the ambulance service they were advised to go to hospital." The firefighters assessed and checked and then allowed to go home.
The fire service said an investigation into the fire is ongoing.
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